It's funny because just recently on the healer forum there was a huge discussion about how BLMs dislike Arrow IMMENSELY during their AoE rotation because it doesn't allow them enough MP ticks when they go from Flare to Transpose --> Fire III --> Fire II --> Flare because of the cast time reduction.
Overall, I feel its important to note that Arrow is a decent card but there are benefits and detriments to the card, and probably the only card that has a noticeable detriment compared to things like Ewer or Spire. Just to use the common adage that FFXI players like to use - "It's situational" and I get the impression that most people who talked about Arrow in this thread recently understand that.
As a random thought and as a casual DRG player, I feel sticking a Fracture into your rotation if you happen to get a single target arrow gets around your GCD issues but will exasperate your TP issues further due to the 80 TP use. Effectively Arrow gives you one additional GCD assuming you have a 2.4 GCD normally to fit 10 GCDs into the 24s buff duration of HT so Fracture gives you that one GCD filler within those 24s. I will admit I haven't actually gotten further with this and it's just been a thought in my head since around 3.2 and I don't really play DRG anymore and focus more on MCH due to my raid group.
I think I'll just drop the topic from here but I did like reading the discussion on it even if it detracted from the overall theme of this thread. I will just leave one food for thought regarding Arrow - Even if you dislike the Arrow buff, leave it anyway. Play as thought you still have a 2.5s GCD and keep Arrow on so it buffs your TP-free auto attacks.